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fidvo · 01-28-2025, 02:34 PM

I recently went through a merge process to combine some of my libraries in order to reduce the number I have, so here are some useful notes that I discovered through experience. I know you said you don't have any customizations, so much of this won't apply. However, I'm posting this for the sake of anyone else who might come across this thread in the future with a similar question.

The basics of merging libraries is straightforward, but because different libraries may have different setups, you'll need to spend some time making decisions about the setup of your merged library.

1. Decide what to do about your custom fields before merging your libraries.

After creating your new "merge" library with the same structure as one of your old libraries (see the post by theducks above), copy a single book from the second library to the merge library. If it pops up a window asking what to do about fields that are not in the merge library, you'll have to make a decision about what to do with these new fields.

The easiest is to simply have Calibre add them to the new library automatically, but I found that I had some custom fields with different names that served the same purpose in the original libraries. I first changed the field name in one of the libraries before merging them. I also found that there were some custom fields I had set up for a certain purpose but never actually used, so I chose not to add these to the new library.

I even decided to change the way how I record certain information because I used a different work flow in the two different libraries and realized that by merging some fields into a single tag-like field I could use the same workflow on both libraries (and by extension, in the merged library).

Note that any time you change your custom fields, you may need to adjust settings in your library based upon these changes.

2. Decide whether you'll need to store the information about which library each book originally came from.

I recommend storing this info at least temporarily because there's a good chance you'll need to do some cleanup and normalizing after you merge the libraries, and being able to filter on that information will likely save a lot of time.

If you don't already have a field or other way that identifies this, you can always stick the original library name into the Tags column before copying the books over.

3. Related to the above, think about what Virtual Libraries you'll need in the new library.

If you're not already using VLs, consider setting up a virtual library based on your original libraries. If you're already using VLs, you'll probably want to re-create them all in the new library. However, in my case I found that I wasn't actually using them all that much, so I decided to go with an entirely new virtual library scheme in the merged library.

4. Make a plan for what to do about the Tag Browser and Edit Metadata window.

Especially if you have a lot of custom fields and merging the libraries will create even more, you'll need to decide which fields to put on the Tag Browser and Edit Metadata window, and in what order. In my case, merging the libraries changed my work flow and therefore certain fields became more important, so I put them higher in the order of both the Tag Browser and Edit Metadata windows.

5. Check your Save to Disk template and metadata plugboards.

If these are different in the original libraries, you'll need to decide which one to keep, or even throw them out and start from scratch.

6. Check your plugin settings.

I'll use View Manager as an example, because that's one I use all the time. Due to different fields and different ways of doing things, I had significantly different views set up in the View Manager plugin. I realized I didn't actually use a lot of them, so I took the time to decide which ones to keep. Because I made some changes to the fields, I also had to make some changes to the existing views. After merging the libraries I had to re-create some of my views.

The same thing applies to other plugins, especially if they depend upon custom fields and you've made changes to your libraries in preparation for merging them.

7. All the above may seem overwhelming, but it's not as bad as it seems. The most important rule is to not lose any information. Fixing settings in your library is a bit of a hassle, but it only has to be done once. You could always just copy the books over, having Calibre add the custom fields that aren't already in the merge library, then clean it all up afterward.

01-28-2025, 02:34 PM	#6
fidvo Addict Posts: 309 Karma: 1645952 Join Date: Jun 2012 Device: none	I recently went through a merge process to combine some of my libraries in order to reduce the number I have, so here are some useful notes that I discovered through experience. I know you said you don't have any customizations, so much of this won't apply. However, I'm posting this for the sake of anyone else who might come across this thread in the future with a similar question. The basics of merging libraries is straightforward, but because different libraries may have different setups, you'll need to spend some time making decisions about the setup of your merged library. 1. Decide what to do about your custom fields before merging your libraries. After creating your new "merge" library with the same structure as one of your old libraries (see the post by theducks above), copy a single book from the second library to the merge library. If it pops up a window asking what to do about fields that are not in the merge library, you'll have to make a decision about what to do with these new fields. The easiest is to simply have Calibre add them to the new library automatically, but I found that I had some custom fields with different names that served the same purpose in the original libraries. I first changed the field name in one of the libraries before merging them. I also found that there were some custom fields I had set up for a certain purpose but never actually used, so I chose not to add these to the new library. I even decided to change the way how I record certain information because I used a different work flow in the two different libraries and realized that by merging some fields into a single tag-like field I could use the same workflow on both libraries (and by extension, in the merged library). Note that any time you change your custom fields, you may need to adjust settings in your library based upon these changes. 2. Decide whether you'll need to store the information about which library each book originally came from. I recommend storing this info at least temporarily because there's a good chance you'll need to do some cleanup and normalizing after you merge the libraries, and being able to filter on that information will likely save a lot of time. If you don't already have a field or other way that identifies this, you can always stick the original library name into the Tags column before copying the books over. 3. Related to the above, think about what Virtual Libraries you'll need in the new library. If you're not already using VLs, consider setting up a virtual library based on your original libraries. If you're already using VLs, you'll probably want to re-create them all in the new library. However, in my case I found that I wasn't actually using them all that much, so I decided to go with an entirely new virtual library scheme in the merged library. 4. Make a plan for what to do about the Tag Browser and Edit Metadata window. Especially if you have a lot of custom fields and merging the libraries will create even more, you'll need to decide which fields to put on the Tag Browser and Edit Metadata window, and in what order. In my case, merging the libraries changed my work flow and therefore certain fields became more important, so I put them higher in the order of both the Tag Browser and Edit Metadata windows. 5. Check your Save to Disk template and metadata plugboards. If these are different in the original libraries, you'll need to decide which one to keep, or even throw them out and start from scratch. 6. Check your plugin settings. I'll use View Manager as an example, because that's one I use all the time. Due to different fields and different ways of doing things, I had significantly different views set up in the View Manager plugin. I realized I didn't actually use a lot of them, so I took the time to decide which ones to keep. Because I made some changes to the fields, I also had to make some changes to the existing views. After merging the libraries I had to re-create some of my views. The same thing applies to other plugins, especially if they depend upon custom fields and you've made changes to your libraries in preparation for merging them. 7. All the above may seem overwhelming, but it's not as bad as it seems. The most important rule is to not lose any information. Fixing settings in your library is a bit of a hassle, but it only has to be done once. You could always just copy the books over, having Calibre add the custom fields that aren't already in the merge library, then clean it all up afterward.